Monday, 31 August 2015

What is your reaction to slime? Most people find the substance,
and even the thought of it, distasteful and yet we would not be alive if it was
not for slime in one form or another.

Slime consists of chemical polymers that expand on contact
with water, producing a clear, sticky substance that is ubiquitous and which we
recognise from its slipperiness and its ability to stick to surfaces. The compounds
that make up slime are referred to as exopolymers, or EPS, by those that study
them and they consist principally
of carbohydrates and proteins, although many other chemicals may also be found in
the EPS produced by different organisms. They are truly ubiquitous: bacteria
using them to attach to substrates; single-celled algae release them when producing
an excess of carbohydrate during photosynthesis; and multicellular organisms
use them for protection, locomotion, to aid in feeding, to aid buoyancy, and as
a means of attachment [1].

During evolution, some cells in multicellular organisms became
adapted to have the sole function of producing the EPS that result in
slime. These goblet cells (see above) discharge their contents to become
hydrated and we are familiar with the resulting sliminess of animals like
worms, slugs and fish.

I talked about EPS to an audience of trout fishers and
this was recorded by the Wild Trout Trust [2] and one of the illustrations is
shown below, together with the link to the video. I could only give a very few examples,
but you get the drift of my talk: EPS are everywhere and yet they are largely
ignored, even by scientists who should know better. Of course, there are
prejudices to be overcome and at one conference dinner I was given a special
prize for "the most revolting talk" given during the sessions. An
award made in good humour, of course, but indicating that the subject was one
that most find unpleasant. This is a pity, because EPS are one of the most
important families of chemicals known.

It is fair to say that humans would not exist if it was not
for slime. This argument has two components: one that develops ideas on the evolution
of humans and the other on the very important role slime plays in allowing our
survival. Our most distant ancestors lived in water and left this medium when
fish transitioned into the amphibians (and then into reptiles and mammals). Reptiles
and mammals have body coverings that reduce the loss of moisture, something
that is a threat to amphibians and also the first fish making visits to land. Anyone
handling a fish is aware that they have a slippery covering and this protects
the animal from attack by parasites and may aid locomotion: it is a feature
that is retained by amphibians and serves to reduce water loss from their
bodies when they are exposed to the air for long periods. It is also a common
feature among soft-bodied terrestrial invertebrates such as worms and slugs,
while others, like the arthropods, have an impervious exoskeleton that much
reduces the threat of desiccation.

Fish slime protects the gills from abrasion and also provides
a barrier against osmotic stress, a feature that is very important to salmon as
they migrate from the sea to fresh waters. Yet gas exchange occurs from the
water to the mucus and then to the tissue of the gill surface and this is a
feature retained through the evolution of respiratory organs of amphibians,
reptiles and mammals. Human lungs and nasal passages have a coating of mucus,
moved by cilia that are a throwback to our very ancient protozoan ancestors,
and it can be so plentiful that it has to be removed by blowing, coughing, or
swallowing, the latter normally being a continuous and unconscious process. In
addition to allowing gas exchange, this mucus acts as a trap for particles,
both living and dead, and it is a convention that we blow an excess of the
slime into handkerchiefs, often noting the extent of hydration once the mucus
becomes dried, demonstrating admirably the extent to which the EPS had undergone
considerable expansion when in contact with water. Larger quantities of slime
than usual are produced when this first defence mechanism is triggered by infection.

It is not only nasal, and bronchial, tissue that produce mucus
in humans, and other mammals, as slime is also found in the digestive tract and in the reproductive system. The slippery quality of mucus acts as a
protection for the oesophagus and slime is produced elsewhere in the gut to
allow smooth passage of the contents while protecting the wall of the
digestive tract. The mucus is not broken down by enzymes and, when aqueous solutions
of food chemicals are removed, characteristic compacted faeces result. These
are bound with slime produced originally by the gut wall and also by EPS released by the
many micro-organisms that are resident within the digestive tract; the
microbes protecting themselves against digestion by secreting EPS that then become
a binding material for the faeces.

The final use of slime in humans is in reproduction and, especially,
in allowing the migration of sperm deposited within the female genital tract.
Each sperm swims within seminal fluid that contains EPS and then traverses the cervical
mucus and onwards into the uterus, where one sperm fertilises a waiting
egg, if one is present. It should also be pointed out that mucus provides a
lubricant to facilitate copulation.

Vital rôles indeed and it is fair to say that we would not exist without
slime in one form or another, nor would very many other organisms

Having read this far in the blog post, what are your
reactions? Perhaps you agree that I deserve to be thought revolting in writing,
and talking, about such things, even though I respect proper taboos in polite
company? Yet I am only highlighting the remarkable diversity of uses for slime
and EPS and this deserves to be much better known, rather than being given the "Ugh!
response" that seems to be most people's reaction to the subject. Why
do we feel that way?

Thursday, 20 August 2015

It is easy to kill micro-organisms, plants and invertebrates
and even a pleasurable act when these cause infestations. I find it more difficult to
kill many vertebrates, especially mammals and, when writing the blog post about
Taking Life [1], my thoughts turned
to the theoretical consideration of whether I could kill another human. The answer
was a clear "No" and that extended to warfare, even when individuals
are removed from their background and one has no knowledge of them, or of their
family and friends. I'm not sure that I could live with the thought of having killed
another human, even when my own life was threatened. It's not an assumption
that I am keen to test.

As a result of my views on killing other humans, I am firmly
against capital punishment, yet recognise that it is practised in many
countries and has been for centuries. Indeed, one of the most famous examples
of capital punishment occurred two thousand years ago with the crucifixion of
Christ and the religion would not
exist if Christ had not been killed and then risen from the dead. From this
perspective, capital punishment is fundamental to Christianity and provides an
exception to the moral code of the Judaeo-Christian tradition given by God in
the Ten Commandments [2].

The crucifixion of Christ was carried out alongside that of
two other "criminals" (omitted by Giotto in the fresco shown above)
and it was intended as a spectacle, this being the custom of the time.
Executions continued to be held in public in Western countries until recent
times and they occur today in the Middle East and elsewhere, both as a warning
and as a form of macabre entertainment. Of course, I refer here to
state-sanctioned murder, rather than the execution by terrorists of hostages,
or of citizens who are deemed to be out of line with a religious or political
principle. Capital punishment is a deliberate act of killing, usually carried
out weeks and months after a trial and, bizarrely, in countries like the USA,
this delay can extend to decades.

Capital punishment requires an executioner (or
executioners). Firing squads have traditionally involved a number of shooters,
some of whom have live ammunition and others blanks. This lessens a sense of
responsibility for taking life when the executioners are coerced into having to
take part. In most other forms of capital punishment there is one executioner
and they may be remote (as in lethal injection, gassing, or electrocution) or
be involved directly (as in beheading, the use of the guillotine, and hanging).
The latter executioners know only too well that they are responsible for taking
the life of another human and do so legally.

Hanging remains one of the most frequently used forms of capital
punishment and, while the act is usually witnessed by prison officials and some
others, it is mostly carried out in private. In some high profile state killings,
the execution has been recorded on film or video to serve as confirmation that
the act has taken place, but this is exceptional. There is a tradition that
hangmen used by the state (are there any hangwomen?) are selected for their
knowledge and ability to ensure clinical dispatch and some learn these skills
from within a family tradition of having the role, learning by stages until
able to perform a hanging themselves. How are they affected by the
experience?

The following quote is from a BBC article [3] that includes
an interview with Sabir Masih, a hangman in Pakistan:

"I feel nothing. It's a
family thing. My father taught me how to tie the hangman's knot, how many coils
etcetera, and he took me along to witness some hangings around the time when I
was being recruited."..

.."My only concern is to prepare
him [the victim] at least three minutes before the time of hanging. So I remove
his shoes, put a hood on his face, tie his hands and feet, put the noose around
his neck, make sure the knot is placed below his left ear, and then wait for
the jailer's signal to pull the lever."

There is no pre- or post-hanging
psychological counselling for hangmen, and no limit to the number of hangings
one executioner may perform before he is given a break.

Mr Masih says he doesn't need
either.

Not all hangmen have that reaction and one the chief executioners
in England, John Ellis, committed suicide because of the stress created by his
job, and of one execution in particular. A reporter for The Rochdale Observer interviewed Ellis's wife shortly after his
funeral and she mentioned the hanging of Edith Thompson, carried out by her
husband on 9th January 1923 [4]. The execution, and its preliminaries, are
described in the book Criminal Justice
by René Weis [5] and the distinguished
Shakespearean scholar describes the events leading up to Edith Thompson's
conviction for the murder of her husband. It is a harrowing, and tragic, story
and I found some sections of the book distressing to read. Despite the verdict of
the court that she was guilty of murder, Weis shows us that this was a
miscarriage of justice.

Edith had brief, passionate encounters with Freddy
Bywaters, a young merchant seaman, during his short return visits to England
between voyages to Australia and the Far East, but it was Bywaters alone who
killed her husband, Percy. In the photograph below, posed deliberately by
Edith's brother, Edith is flanked by Percy on the right and by Freddy on the left - eighteen
months after the photograph was taken all three would be dead. There is no
dispute that Freddy killed Percy, although there has been discussion of the
circumstances that led up to the assault and, to the end, Freddy maintained
that Edith was innocent and had nothing to do with the final act.

Especially harrowing in Criminal
Justice are the descriptions of the extreme anguish that Ethel suffered
while on remand and when awaiting execution. In the weeks leading up to 9th
January 1923 she was so distressed that frequent doses of strong sedative had
to be administered and she was near unconscious when warders effectively
carried her to the scaffold after Ellis had entered her cell to prepare her for
the execution (was this his first contact with Edith after being summoned from
Rochdale?). When the act took place, there were dreadful consequences, as the
drop caused severe haemorrhaging and there was a lot of cleaning up to do. Ellis
and the prison staff were obviously very upset by this and they may also have
suspected that she was innocent of a capital offence. Several journalists took
up both Edith's and Freddy's cases and argued against the verdict of the court
and there was wide coverage of the case [5] and of subsequent events.

I won't dwell more on that story, but it is relevant to
discussions on the use of the death penalty as a means of state punishment. If
the cold-blooded nature of the act wasn't bad enough, the mental anguish of
waiting for "justice", the agony of visits from family and friends as
the day draws nearer, and the effect on all the staff are quite enough to
convince me that capital punishment cannot be justified, even for the most
heinous crimes.

Friday, 7 August 2015

The headline on page 6 of The Independent on Saturday 1st August read [1]: 'What is fun about
death and the killing of a beautiful creature?'. It was a quote from an interview
by Jonathan Owen with the campaigner Virginia McKenna and focussed on the
killing of a lion by a trophy hunter, but it set me thinking more widely about
my attitude to killing organisms. I maintain that all creatures are beautiful,
so, for me, the adjective is redundant.

I'll begin with two examples that only loosely fit the
definition of a creature. As someone who has had a close encounter with E. coli (below, top left), I am very thankful
for antibiotics and their power to kill the bacteria. However, studies in microbiology
reveal not only a beautifully adapted organism, but one with tremendous powers
of reproduction and the ability to fend off the defence mechanisms of the host.
Killing them when they infect areas of the body other than the gut brings a
great deal of relief but I wouldn't describe it as being fun. The same applies
to the presence of weeds like dandelions in the garden, especially the lawn.
No-one could dispute that they are beautiful plants, but we like them in the countryside
and not messing up the neat arrangement of plants that we like to culture.
Killing weeds never involves thoughts of regret at extinguishing the life of
another creature, at least in my experience.

Having spent time in Northern Scandinavia on research
visits, I know something about high densities of mosquitoes [2]: who was it who
said they enjoyed the high-pitched noise of mosquito wing beats and likened it
to singing? Adult females require blood before they can mature their eggs and
they are both persistent at finding hosts and, despite their noisy flight,
usually land unnoticed. Unfortunately, I react badly to mosquito bites and
invariably get lots of itchy lumps as a result. Creams and anti-histamine
sprays are of some assistance, but I try to kill the insects before attack, if
at all possible. Not exactly the fun of the headline in The Independent, but certainly pleasurable. Yet I have studied
larval mosquitoes in some detail, as I have the larvae of other biting flies,
and I am amazed by the evolution of their feeding structures and the metamorphosis
that results in such different body plans as those of the larvae and adults. I
retain a sense of wonder, but this is not in my mind when I kill biting flies
(and I've killed millions of their larvae). However, there are plenty left
after my efforts.

Other beautiful creatures include wasps and blowflies
(above, lower). All of us are amazed at the structure of wasp nests: the way they
are constructed; the social behaviour of the inhabitants; and the capacity for
workers to hunt and gather to bring food to bring to the nest. Wasps are
brightly coloured to give a warning that they sting and we react to that, even
though it evolved long before humans appeared on the Earth. Indeed, almost any
insects with black and yellow striped abdomens receive the same treatment as
wasps as we try to brush them away and, preferably, swat them. As I write, we
have a wasp nest nearby and the workers often enter our house through open windows.
Despite my admiration for the structure and lifestyle of wasps, I kill these
intruders with relish and would ideally like the nest removed, wherever it
might be. It's the same with blowflies and house flies and their beautifully
adapted maggots [3]. I kill those with the same degree of pleasure.

All the examples thus far are of creatures which either
cause harm or irritation to us, or to our immediate surroundings. What of the killing
of creatures for food? Our hunter-gatherer ancestors captured animals to eat
and we can still do this if collecting, fishing or shooting. However, we are now
mostly dependent on buying animals that have been killed by
someone else, although blue mussels are sold alive before we kill them by
tipping them into a pan of boiling muscadet [4]. The food industry is geared to
providing us not only with killed animals, but also gutted fish, or butchered meat,
although this processing is largely hidden from us. Fish are caught at sea by
lines or trawls, or gathered from large enclosures in fish farms, and they are allowed
to die before being gutted and packed on ice. Meat comes mainly in the form of
chickens, turkeys, sheep, cows and pigs that are farmed, with the latter three transported
first to markets and then on to abattoirs for slaughter. I've visited an
abattoir and it was not a pleasant experience, but not sufficiently unpleasant
to stop me from being an enthusiastic omnivore.

During disease outbreaks, it is common for farm animals to
be shot in situ and their carcases
burned or buried. It strikes me that killing livestock on farms is preferable
to the market-abattoir route, although many may prefer the killing to continue
being hidden from view. At least some chickens and turkeys are killed on the
farms where they are reared, but the conditions in which they live vary greatly.
The intensive rearing of battery chickens for egg production is a case in point
and I still remember vividly the smells, sounds and sights of a battery rearing
unit that I visited forty years ago. Slaughter is just part of a brutal
process, as it is with other intensively reared farm animals, and slaughter on
site, or nearby, is hardly the compensation it would be for animals that are
allowed a (relatively) free range.

Shooting livestock would be little different to hunting game,
something that I've enjoyed. As I do not wish to kill the animals myself, my
role in rough shoots is as a beater, walking up the game and watching the
dogs quartering the ground ahead of the line of guns. It is a good day out and
worth it just to watch the dogs in action, and most birds on shoots I've
attended are shot cleanly. In addition, there is the prospect of being paid for
my pleasure in the occasional gift of a bird and I'm very fond of game of all
kinds. My sole experience of hunting deer came when I accompanied a friend who
is highly experienced stalker. We could see roe deer in a clearing and I was
told to lie down and watch while he moved through the wood to get into a good
position to shoot. After minutes, there was a loud crack and the deer dropped
dead and we were quickly on to it. We immediately performed the
gralloch, which was not upsetting to me as it was no different to the dissecting
that I had done as part of my Zoology training. The deer was grazing one minute
and dead the next and I thought that was rather good, just like the killing of
pheasants that died shortly after they were put to flight.

Killing to prevent attacks, or for food, seems acceptable to
me, as long as death is rapid. Killing for fun is less acceptable, although I
recognise that some people get pleasure from slaughtering large numbers
of fish and higher vertebrates, enjoying in this way their power over Nature.
Selecting the killing of a lion, albeit in a gruesome manner,
highlights our approach to the killing of all living creatures, each a remarkable
example of the power of evolution.